Formal:
* Meus queridos amigos: This is the most literal and formal translation.
* Meus estimados amigos: This is slightly more formal than "queridos" and emphasizes respect.
Informal:
* Meus amigos queridos: This is a common and affectionate way to address friends.
* Meus amigos: This is the most casual option, simply meaning "my friends".
Even more affectionate:
* Meus amados amigos: This translates to "my beloved friends" and is very affectionate.
* Meus queridos: This is a shorter and more informal version of "meus queridos amigos", and it emphasizes affection.
The best option for you will depend on your relationship with the people you are talking to and the tone you want to set.